How to reduce drawing soap consumption

On wire drawing lines, drawing soap usually appears on the purchasing side as a single line: so many kilograms a month, so much money. When that line grows, the first reflex is generally the same — put less soap in the box, stretch the filling interval, try a cheaper grade. Yet the kilograms on the invoice are not the kilograms that reach the wire surface. Part of the soap purchased leaves the line without doing any work at all; another part becomes unusable without ever leaving its packaging.

Genuinely reducing soap usage runs through cutting loss, not cutting consumption. To do that you first have to distinguish where the soap goes, and then know which direction each variable pushes. This article works through the Kimkal drawing soap range to cover the loss items, the parameters affecting usage, how to track consumption per unit and why the “save by cutting soap” trap raises total cost — in language shared by process and purchasing.

Where does the soap you buy actually go?

Thinking of the soap consumed on a line as a single item hides where the improvement should be made. In practice consumption splits into at least five destinations, and only one of them does any real work:

• Useful film: the part that adheres to the wire surface and becomes a lubricating film at the die entry. This is the share that does the actual job; we set out how it forms in dry drawing soap film stability.
• Soap spilled and flung out of the box: at the points where the wire enters and leaves the box, particularly at high speed, loose powder is thrown out. The box lid, its alignment and the wire entry/exit geometry directly determine this loss.
• Soap shed at the die exit: deposits that have not keyed into the surface, or are too thick or too coarse-grained, flake off immediately after the die. That soap was bought and carried but never became film.
• Soap drawn into the dust collection system: if the extraction rate and the position of the intake are wrongly set, the system pulls usable soap along with dust. The amount of soap accumulating in the filter bags is the most tangible indicator of this loss.
• Soap that takes up moisture, cakes and is scrapped: open packaging, a damp store and mixed stock rotation lead to soap being discarded without ever entering the line.

This distinction has a practical consequence: however much soap accumulates on the floor under the line, around the box, behind the die block and in the dust collection filter, that much of your consumption is already loss. Putting less soap in the box shrinks none of those items; it only shrinks the useful film share. The place to improve is not the film itself but the share that never becomes film.

The variables that drive consumption, and their direction

Soap usage is not a quantity managed by a single setting; it is the joint result of decisions taken at many points on the line. The table below summarises the variables most often met in the field, the direction in which they affect consumption and what to do about each. Rather than promising a percentage saving, we should say at the outset that you need to verify the effect of every row on your own line by measurement.

The first two rows of the table matter especially, because the source of consumption complaints is usually not the soap itself but the carrier layer beneath it. A porous, evenly crystalline zinc phosphate coating holds the soap and carries it to the die; an inadequate coating cannot hold the soap on the surface. Adding more soap suppresses the symptom in the short term but grows both usage and die wear together. For how to verify coating weight, see coating weight measurement.

The soap type itself also writes to the consumption side. Reactive soaps, which react with the phosphate layer, build a chemically bonded layer on the surface; neutral soaps leave a mechanically adhering film. The two families are not consumed in the same quantity on the same line, nor do they shed the same amount. Making the choice on price per kilogram alone is misleading; we compare the families in drawing soap selection.

You cannot improve what you do not measure

In most plants soap consumption is known only as a monthly kilogram total. Because that figure varies with production volume, product mix and the number of shifts worked, on its own it says nothing. What is meaningful is unit consumption normalised to production:

• kg soap / tonne of wire drawn — gives a common base on lines producing a range of diameters.
• kg soap / km of wire drawn — a more sensitive indicator on lines running a fixed diameter, because soap consumption relates to surface area rather than mass.
• Separation by product/diameter — mixing fine and heavy wire into the same average hides the real change.
• Loss share — the amount of soap collected from the dust filter and floor cleaning over a given period allows the non-useful share to be tracked roughly.

There is no absolute “correct” target for these figures; every line differs in diameter, pass schedule, speed and phosphate quality. What is valuable is establishing a reference period that runs trouble-free on your own line and following the trend. If unit consumption is drifting slowly upwards, the soap has usually not changed; a crust has formed in the box, coating weight has slipped below target, a die has worn or the store has taken up moisture. Without that tracking, the only visible thing is a growing invoice, and the decision gets made from the wrong place.

The false economy of cutting soap

Soap is one of the most visible consumable items on the line; die life, scrap and downtime sit on different budget lines. That separation easily leads to the wrong optimisation: to shrink the soap line the box is filled less, a cheaper and coarser grade is bought, or the filling interval is stretched. In the short term the soap item falls. But the film thins, metal-to-metal contact starts at the die entry, die wear accelerates, scratches and dimensional deviation on the wire increase, break frequency rises and line stoppages lengthen.

The money saved on the soap budget is usually more than repaid out of the die change and downtime budget. The problem is that those two lines never appear side by side in the same report.

The right comparison is made on the total cost of ownership of lubrication. Within the same product group, the same pass schedule and the same period, these items should be read together: soap consumption, die change count and die cost, downtime caused by breaks, reject/scrap rate from surface quality, energy consumption of the drawing motor and, if applicable, the cost of a post-drawing cleaning step. How friction ties these items together is explained in friction in cold forming.

The reverse is also true: increasing soap is not a solution either. Excess soap that cannot key into the surface builds up in the die cone and leaves marks on the wire, increases dusting and the dust collection load, and sheds at the die exit as direct loss. In other words too little and too much soap arrive at the same place — higher cost. What you are looking for is not quantity but continuity of the film.

Practical steps to reduce loss

The interventions that permanently lower unit consumption generally have to do not with the soap itself but with the discipline around it:

1. Fix the head of the line. Oil and contamination left on the surface spoil phosphate quality, and a poor phosphate will not hold soap. The efficiency of the degreasing stage is written directly into soap usage.
2. Keep coating weight and crystal structure in the target range. Without a stable phosphate side, no adjustment on the soap side gives a lasting result.
3. Manage the soap box as equipment. Fill level, filling interval, complete emptying and cleaning interval should be a written routine; the “top it up when it gets low” practice grows the loss.
4. Prevent fling-out physically. A box lid, entry/exit wipers and correct alignment noticeably reduce the soap thrown out at high speed.
5. Set up the dust collection system. The intake should take free dust from the surroundings, not soap from the box. Check the amount of soap accumulating in the filter periodically.
6. Fix the store. Sealed packaging, stacking on pallets, a dry and cool area, distance from heat and steam sources and first in first out rotation eliminate soap scrapped without ever entering the line.
7. Choose particle size and soap character for the line speed. Decide from line data, not from the price list.
8. Report unit consumption (kg/tonne or kg/km) regularly and show it in the same table as die, scrap and downtime data.

What these steps have in common is that none of them cuts the amount of soap directly. All of them make a larger share of the soap purchased turn into useful film. That is how usage falls: without weakening the film, without shortening die life. The same discipline shrinks a second item too: soap carried in excess also increases the residue cleaning load after drawing.

In summary

Drawing soap consumption is an output of the line, not of the soap type. The weight and crystal structure of the phosphate coating, the design of the soap box and the filling discipline, drawing speed and reduction distribution, particle size, extraction setting and storage conditions determine it together. Any attempt at saving made without knowing which direction these variables push carries the risk of shrinking the soap line while growing the die, scrap and downtime lines.

Producing phosphating chemicals and drawing soaps since 1982 from its 4,000 m² plant in Kartepe / Kocaeli, Kimfosan is Türkiye's leading drawing soap manufacturer. If you would like to assess your line's unit soap consumption together with KİMSOL phosphate coating and Kimkal soap parameters, talk to our technical team; for product data sheets and technical documents see our document centre.